THE PITUITARY BODY 



believed to vary in significance as a cause of breast develop- 

 ment. Certainly, it is much less important than oestrogen 

 and is thought to act only after some growth, especially of 

 the ducts, has already occurred, following the secretion or 

 administration of oestrogen. Most authors have concluded 

 that the secretion of the corpus luteum is of definite im- 

 portance in bringing about alveolar development in the rab- 

 bit's breast, provided that growth of the ducts has been 

 stimulated by oestrogenic hormone.^ Lactogenic hormone 

 then readily produces or "releases" the secretion of milk. On 

 the other hand, in the guinea pig and rat, progesterone ap- 

 pears to be of little significance in supplementing the effects of 

 oestrogens on mammary growth and development (Gardner 

 and others, 1935; Repetti, 1936; Astwood and others, 1937; 

 and Nelson, 1937).^ 



The effect of androgens on the development of the mammary 

 glands. — As in female rats, the post-pubertal development of 

 the breasts in male animals is prevented by gonadectomy. 

 Testosterone propionate, although without oestrogenic ef- 

 fects, will cause mammary development in spayed rats (Mc- 

 Euen, Selye, and Collip, 1936). The authors injected 3 mg. 

 of testosterone propionate as the total dose over 1 1 days. 

 Astwood, Geschickter, and Rausch (1937) concluded that tes- 

 tosterone can bring about, in young male rats, mammary de- 

 velopment corresponding to that in adult males. Large doses 

 of the hormone, although causing cyst formation and an in- 

 crease in the fibrous tissue, produced no development of the 

 mammary tree such as followed the administration of oes- 

 trone. Apparently the effects of testosterone on the breast, 

 like those of an oestrogen, are secondary to the secretion of 

 an anterior pituitary hormone; hypophysectomy prevents 

 such effects (McEuen, Selye, and Collip, 1937). 



^ Gardner, Gomez, and Turner (1935) ; Anselmino, Herold, and Hoffmann (1935) ; 

 Macdonald, Pallet (1936); Gillard (1937). 



' Such observations should be made in spayed animals, inasmuch as the oestrogen 

 may bring about the new formation of lutein tissue by increasing the rate of libera- 

 tion of luteinizing hormone from the anterior pituitary. 



[156I 



